Doubters of the value of the Endangered Species Act need only drive across the Waldo-Hancock Bridge or, or in some cities, work in a downtown office building to see the dividends of the federal animal and plant protection law. Perched high on bridge spans, diving from cliffs at Acadia National Park and skyscrapers in Boston, peregrine falcons have made a comeback. The success story is due to the outlawing of a deadly pesticide and a lot of human intervention.

In 1970, there were only 39 known nesting pairs of the falcons in the United States. At that time, peregrine falcons had disappeared east of the Mississippi River.. The decline was blamed on pesticides, primarily DDT, which is known to thin egg shells. After DDT was banned in 1972, the birds began to recover. The falcons, which dive on their prey at speeds of up to 200 miles per hour, were bred in captivity, with birds reintroduced in the East, where they had not lived for generations.

Today, there are about 2,000 nesting pairs nationwide with 16 pairs living in Maine. Oddly, recovery numbers in Maine have been hampered by the fact that falcons released here, much like the state’s youth, are drawn to the big cities. Unlike their human counterparts who go in search of high-paying jobs and excitement, the birds are lured by the slow, fat pigeons that live in abundance in urban parks and on skyscrapers. Between 1984 and 1997, 150 baby falcons were released in Maine. A female peregrine falcon released in Acadia National Park in the 1980s was later found nesting atop the John Hancock Building in Boston.

About the size of crows, the birds were one of the first animals to be protected under the ESA, which was enacted in 1973. They were removed from the list in 1999. Last week, the U.S. Fish and Wildlife Service approved a 15-year program to monitor the world’s fastest bird.

One of the most unusual aspects of the peregrine falcon recovery is that is has been so visible to the public. Mating, fledglings’ first harrowing flights and the capture of stunned mourning doves have been witnesses by office workers and those who watch nesting sites via television and the internet. While it is unusual to have “wild” animals thrive in an urban setting, the success of peregrine falcons shows that humans and endangered species can co-exist.

Rather than weakening the ESA and other animal protection acts, creative approaches can be found to accommodate endangered species and people. Another example is the thriving lynx population in Maine’s industrial forest. Whether dive-bombing their prey from The Precipice in Acadia or a Boston building, peregrine falcons are the perfect symbol of the act’s success.